In the prior art, apparatuses and systems have been used to control an air conditioner on the basis of position information of a user of a building in which the air conditioner is installed. For example, Japanese Laid-open Patent Publication No. 2014-1738181 discloses an air-conditioning control apparatus to acquire a current position of a portable terminal carried by the user who is away from the building, and control the air conditioner on the basis of a distance between the portable terminal and the air conditioner. This air-conditioning control apparatus determines that the user is about to return and starts up the air conditioner when the distance between the portable terminal and the air conditioner, i.e., the distance between the user and the air conditioner is equal to or less than a predetermined threshold value. Additionally, when the rate of decrease of the distance between the user and the air conditioner is less than a predetermined threshold value, the air-conditioning control apparatus determines that the user is not approaching the air conditioner and stops the operation of the air conditioner in cases in which the air conditioner has been started up. Therefore, this air-conditioning control apparatus can suppress energy needlessly consumed by the air conditioner by controlling the air conditioner in accordance with the current position of the user when the user is returning.